The present invention relates to a slaving motor which exerts precession moments directly on the rotating rotor of a gyroscope, which moments are controlled by the position of components of the slaving motor in relation to the rotor. The invention also relates to gyroscopes designed to use such a slaving motor.
Slaving motors which act directly on a rotating rotor are of particular importance for gyroscopes whose rotors have three degrees of rotational freedom relative to the fixed parts surrounding them, that is to say gyroscopes in which the rotor is not first of all mounted to rotate about its axis of spin in a first gimbal whose position represents the position of the vector axis which in turn represents the inertial measurement data given by the gyroscope. Among gyroscopes of this kind are those whose rotors are connected by rotating joints to a drive shaft mounted directly in the rotor frame and particularly gyroscopes having rotating resilient joints, which in turn encompass the class of dynamically tuned gyroscopes, which are produced in many forms.
To simplify them and to reduce the number of components and potential sources of error, it is of advantage in certain gyroscopes of which embodiments will be described below, to control the precession moments exerted on the rotor not by the current to the slaving motor but by the position in relation to the gyro-rotor of a magnetic arrangement which is permanently excited or constantly excited over a period of time. This advantage is afforded in particular when a precession moment is to be generated either proportionally to the angular deviation of the rotor relative to the gyro-frame, in which case the magnetic arrangement may be fixed to the frame, or else as a function of the angular position of the rotor relative to the vertical, in which case the magnetic arrangement may be arranged on a component whose position is governed by the force of gravity. The first requirement exists typically in rate of turn gyroscopes and the latter in different figurative forms in compasses and attitude gyroscopes.
It is an object of the invention to provide a position-controlled slaving motor which acts directly on the rotating rotor of a gyroscope and which exerts thereon a precession moment which is determined solely by the angular position in relation to the rotor of a magnetic arrangement surrounding the gyroscope, except for the very slight effects of technical shortcomings, and which makes it possible for the rotor to be simply constructed from totally non-magnetic and non-magnetisable material. The intention is also to achieve the object of coupling this slaving motor to the earth's field of gravity in such a way that the functions of specific kinds of gyroscope, particularly attitude gyroscopes and gyro-compasses, can be performed.
In accordance with the invention this object is achieved by having part of the rotor take the form of a cylindrical drum whose walls are thin in relation to its diameter and which is made of a non-magnetic material which is a good conductor of electricity, and by having the magnetic arrangement which produces the moments of precession take the form of a magnetic ring which extends round the drum from at least one of its ends and which generates an annular magnetic field which is uniform around the circumference of the magnetic ring, which passes through the drum radially, and which extends for a fraction of the length of the rotor drum, preferably with axial symmetry about the centre point of the rotor joint.
In one embodiment of the invention, e.g. for constructing a gyroscope to measure the inertial speed of rotation of the gyro-frame about two axes, such a gyroscope being referred to here as a two-axis rate of turn gyroscope, the magnetic ring is rigidly connected to the rotor frame in a position such that its longitudinal axis coincides with the axis of the drive shaft.
In a second embodiment of the invention, for example for constructing an integrating rate of turn gyroscope having only one sensing axis, which will be referred to here as a single-axis rate of turn gyroscope, the magnetic ring is arranged to be pivotable relative to the gyro-frame about an axis which lies at right angles to the axis of the drive shaft and which preferably passes through the centre point of the joint of the rotor.
In further embodiments for exerting controlled slaving moments on the gyro-rotor the magnetic ring is connected to the rotor frame so as to be able to pivot about more than one axis which lies at right angles to the drive shaft of the rotor and which preferably passes through the centre point of the joint of the rotor, and means are provided to control the position of the magnetic ring relative to the gyro-frame about one or more of its axes or to exert torque on the magnet ring.
In further embodiments for exerting slaving moments on the gyro-rotor as a function of the angular position of the gyro-frame in relation to the vertical, the magnet ring or one or more of the parts by which it is suspended to pivot in the gyro-frame are given deliberate imbalances relative to the axes of pivot of the magnet ring.
To set the slaving moments in desired directions relative to the directions of moments exerted on the magnetic ring, the magnetic ring and the parts by which it is suspended to pivot in the gyro-frame may be provided with resilient return means which exert torques on the magnetic ring as a function of its deviation from its normal position relative to the drive shaft of the gyroscope. Also, to avoid errors arising from friction in and displacement of the pivot bearings, and to simplify the construction of the gyroscope, it is proposed that the pivot bearings and the resilient return means be functionally combined in the form of resilient joints.